Optimizing whole grain rice fortification using microwave-assisted screw conveying spraying and drying setup: Exploring solution absorption, gelatinization, and micronutrient retention

Abstract

This study presents a novel gelatinization-induced whole-grain rice fortification (GIWGRF) technology using a microwave-assisted screw conveying spraying and drying setup (MASCSD). The process involves microwave-assisted soaking of pregelatinized rice in a micronutrient solution, followed by steam-assisted gelatinization and drying. Rice with an initial degree of gelatinization (DG) of 58.87 ± 2.11 % was subjected to microwave-assisted spray-soaking with NaFeEDTA solution (2125 mg/400 mL) at 0.6 kW/kg microwave power density (MPD) for 20 min, achieving approximately 50 % moisture content. The rice was then steamed for 100 s to enhance gelatinization and micronutrient embedding, increasing DG from 58.23 ± 3.50 % to 75.86 ± 4.15 %. Subsequently, the rice was microwave-assisted dried at 0.6 kW/kg MPD for 65 min, resulting in a final moisture content of 13.21 ± 2.71 % (db). GIWGFRK exhibits similar physicochemical and cooking properties and offers 97.12 ± 2.26 % micronutrient uptake during spray soaking, 89.19 ± 2.33 % washing retention, and 65.77 ± 4.19 % cooking retention. Thus, this technique can be suggested as a practical approach to whole-grain-rice-fortification.

Keywords: Cooking; Gelatinization; Gelatinization-induced-whole-grain-rice-fortification; Microwave power density; Microwave-assisted screw conveyor spraying and drying setup; iron retention.